Ice reinforcement



United States Patent 3,289,425 ICE REINFORCEMENT Adam L. Shrier, Orange,N.J., assignor to Esso Research and Engineering Company, a corporationof Delaware No Drawing. Filed July 27, 1965, Ser. No. 475,237 6 Claims.(CI. 62-68) This invention relates to a method of reinforcing frozenliquids, and more particularly relates to a method for obtaininghomogeneous, frozen liquid compositions containing relatively highconcentrations of reinforcing material.

It is known that the compressive and tensile strengths of pure ice aregreater than those of many concretes, and that the strength of ice canbe appreciably increased by incorporating a finely divided, preferablyfibrous, inert material into the liquid before freezing. Suchcompositions can be used to construct facilities in cold regions such asthe Arctic. They can also be employed in the Torrid or Temperate Zonesprovided there is adequate refrigeration available. For example, suchcompositions can be employed in the construction of storage containersfor liquefied hydrocarbon gases.

The compositions should comprise a substantially v homogeneous mixtureof liquid and reinforcing material.

Moreover, the strength of the frozen composition increasessu-bstantially linearly with the increasing volume fraction of fibrousmaterial that is added to the liquid. There are problems associated withthe mixing of such compositions which here heretofore made it impossibleto obtain substantially homogeneous, bubble free compositions comprisingliquid and relatively large amounts of fibrous fillers.

One problem is that the fibrous fillers usually segregate either bysinking or floating in the liquid at a relatively high rate after thefiller has been admixed with the liquid. Therefore, by the time thecomposition has been frozen, there exist pockets of filler rather than ahomogeneous composition; this segregation causes the material to berelatively weak. One possible solution to this problem would be toreverse the system. In such a system, the major component would be thefibrous material and the liquid would be added only in an amountsufficient to saturate the fibers. The fibers would support themselves,thereby keeping segregation to a minimum provided the liquid weresuitably contained. Such saturated compositions are suitable for manypurposes, but have the disadvantage of being difficult to transport bypumping. In addition, it is economically more attractive to use aliquid, especially water, as the major ingredient particularly intheArctic where it is available in abundance and the fibrous materials mayhave to be transported from another area. There are still otherdifferences between the characteristics of the saturated filler andthose of the composition comprising water as the major ingredient thatmake it desirable to use the latter composition.

The desired homogeneous composition comprising water and from 1 to 100wt. precent based upon the weight of water of a fibrous filler cannot bereadily obtained with some fillers because of the aforementioned problemof segregation. Even if the mixture is frozen quickly in an attempt toavoid substantial segregation, another problem in some instancemilitates against the use of from 30 wt. percent to 100 percent offibrousfiller. The use of some fibrous fillers, e.g. shredded asbestos,promotes the formation of air bubbles in the pores and on the surfacesof the filler; the air bubbles substantially weaken the resulting frozencomposition. Heretofore, the air bubbles have been removed by violentagitation and in some instances by boiling. These means of removing thebubbles are cumbersome and expensive. More- 3,289,425 Patented Dec. 6,1966 over, they are not effective above concentrations of about 30 wt.percent filler becuase of the high viscosity of the composition. Aprohibitive amount of energy is required to drive the air bubbles out ofthe high viscosity composition.

It is therefore an object of this invention to provide a method ofincorporating relatively large amounts of fibrous filler into a frozenliquid composition.

It is a further object of this invention to provide a method ofobtaining substantially homogeneous, frozen compositions comprisingwater and a fibrous filler.

It is still a further object of this invention to provide a method ofobtaining a substantially homogeneous, bubble free frozen compositioncomprising a liquid and relatively large amounts of a fibrous filler.

Other objects of this invention will become apparent as one reads thefollowing disclosure.

Segregation can be significantly reduced .by incorporating a thickeningagent into the liquid in a small amount sufficient to increase theviscosity of the liquid. The thickening agent impedes the rate ofsinking or floating, as the case may be, of the fibrous filler in theliquid. As a result of the early work, it would seem that the use of athickening agent would be contraindicated, for it appeared that highviscosities made it more difiicult to remove air bubbles; this problemis obviated as discussed hereinafter. Experimentation has indicated thatthe thickening agent may do more than increase the viscosity of theliquid, or it may be that the increased viscosity aids in the formationof bonds; for tests comparing compositions comprising water, filler, andthickening agents resulted in stronger compositions than the results oftests of compositions consisting of water and filler. This was true eventhough the latter composition was homogeneous; homogeneity was obtainedin the latter composition by quickly freezing a composition comprisingwater and filler in a laboratory.

Many liquids are suitable for the process described herein provided thatthe liquid can be frozen with refrigeration means that are available atthe place of use. Water is preferred because of its low cost,availability, and relatively high freezing point.

The fillers that are employed in this invention are preferably fibrousfillers such as spun glass, plastic fibers, rock wool, shredded hemp,sawdust (Wood fiber), fiberglass, asbestos, paper, grass, hay, and thelike. In short, suitable fillers can be made from practically anyfibrous material including wastes, scraps, and other inexpensivesubstances. Fillers should be fibrous. The use of dense or compactfillers in the form of beads, chunks, and fragments does not produce thedesired effect. The ratio of fiber length to the diameter of the fibershould be at least 5:1 and preferably greater than 15:1. The strength ofthe resulting frozen composition is directly proportional to the lengthof the fibers. However, the fibers must not be too long or pumping ofthe admixture will be difficult or perhaps even impossible. For mostapplications the fibers should have an average length of from about 4;inch to 6 inches.

The thickening agents of this invention should be soluble in the coldliquid that is used as the major ingredient, and should not be adsorbedby the solid filler to the extent that the thickeners becomeineffective. If water is employed, the thickening agent may (be asynthetic watersoluble gum such as those materials having a polymericbackbone of cellulose. The thickeners sold under the trade name ofMethocel have been found to be particularly effective. Other suitablethickening agents used alone or in combinations include syntheticpolymers containing polyacrylamide, isom-orphous silicates, polyethyleneglycols, and the like. The thickening agents should be added in anamount suflicient to significantly impede the sinking or floating, asthe case may be, of the filler in the liquid. The amount required willdepend upon a variety of factors including the type of filler employed,the type of thickener or mixture of thickeners selected, and thetemperature of the liquid at time of admixing. However, the thickenershould usually be employed in the range of from 0.05 to 5.0 wt. percentbased upon the weight of the liquid.

In preparing the composition for freezing, the thickening agent shouldfirst be added to the liquid medium. and the filler material thereafterincorporated. The use of the thickener significantly reduces, and insome instances completely eliminates, the problem of filler segregation.It permits the obtaining of essentially homogeneous compositions even inthose instances where there is a substantial delay between the time ofmixing and the time of freezing. The thickener is useful over a broadrange of filler concentrations. When certain fillers are used, asubstantially homogeneous, bubble-free, frozen composition can beobtained by the use of the thickener. However, certain fillers, forexample, asbestos, when used in amounts in excess of 30 wt. percentbased upon the amount of liquid employed, promote the formation of airbubbles which adhere to the solid surfaces and which heretofore couldnot be removed from the system without expending a prohibitive amount ofenergy.

The air bubble problem is greatly reduced and in many cases eliminatedin accordance wit-h this invention by utilizing a wetting agent. KnownWetting agents are suitable. For example, if water is the liquid,suitable wetting agents include anionic agents such as sodium benzenesulfonate, short chain C C alkyl aryl sulfonates, short chain dialkylsulfosuccinates, and short chain alkyl sulfates; nonionic compounds suchas C C fatty acid polyglycol esters, and a-lkyl aryl polyglycol estersand their derivatives can also be employed. These wetting agents arepreferred, but are not the only agents that can be employed. Otheragents can be used without departing from the scope of this invention.

The following examples illustrate specific methods of obtaining theobjects of this invention.

Example 1 A thickening agent, sodium carboxymethyl cellulose, isdissolved into water in the amount of 1.0% based upon the weight ofwater. To the solution is added wt. percent (based upon the weight ofwater) of short plastic fibers. The mixture is thoroughly agitated toobtain a homogeneous admixture of filler in water. The admixture is thenfrozen and will be homogeneous despite a time delay that is ordinarilyencountered when such material is used to construct facilities.

Example 2 0.5 wt. percent of a thickener, sodium carboxymethylcellulose, is dissolved in water together with 0.5 wt. percent of awetting agent, sodium dioctyl sulfosuccinate, and 50 wt. percent (basedupon the weight of water) of shredded asbestos is thoroughly admixedwith the water solution. The admixture is then frozen and there resultsa homogeneous, bubble-free admixture despite the fact that asbestosordinarily promotes the formation of air bubbles in water.

Example 3 0.2 wt. percent of a wetting agent, sodium dioctylsulfosuccinate, is dissolved in water. Thereafter, 40 wt. percent ofshredded rock wool, a fibrous filler which ordinarily remains suspendedin water without the aid of a thickener and which ordinarily promotesthe formation of air bubbles, is thoroughly admixed into the watersolution. After freezing, the resulting composition is homogeneous andbubble free.

The invention has been described herein With a certain degree ofparticularity. Various deviations can be made to the concepts describedherein without departing from the scope of the invention.

What is claimed is:

1. A method of obtaining a strong, substantially homogeneous andbubble-free frozen admixture of liquid and a relatively large amount offibrous filler which ordinarily does not remain suspended in said liquidonce dispersed therein and which ordinarily promotes the formation ofair bubbles in the admixture comprising: dissolving a thickening agentinto said liquid in an amount sufficient to increase the viscosity ofsaid liquid, dissolving a wetting agent into said liqud in an amountsufiicient to ensure the wetting of said fibrous filler by said liquid,admixing a fibrous filler into said liquid to obtain a substantiallyhomogeneous admixture, and freezing said admixture.

2. A method of obtaining a strong, substantially homogeneous andbubble-free, frozen admixture of water and a relatively large amount offibrous filler which ordinarily does not remain suspended in water oncedispersed and which ordinarily promotes the formation of air bubbles inthe admixture comprising: dissolving a thickening agent into water in anamount sufficient to increase the viscosity of said water, dissolving awetting agent into the water in an amount sufiicient to decrease thesurface tension of the water, admixing said fibrous filler in an amountof from 30 wt. percent to wt. percent based upon the weight of waterinto the water containing the thickening agent and Wetting agent toobtain a substantially homogeneous admixure, and freezing saidadmixture.

3. A method according to claim 2 wherein said admixture is formed into astructural element prior to the freezing of said admixture.

4. A method according to claim 2 wherein said wetting agent is sodiumdioctyl sulfosuccinate.

5. A method of obtaining a strong, substantially homogeneous, frozenliquid composition comprising: dissolving a thickening agent into waterin an amount in the range of from 0.05 to 5.0 wt. percent based upon theweight of the water sufficient to increase the viscosity of the water,admixing a fibrous filler into said liquid to obtain a substantiallyhomogeneous admixture forming said substantially homogeneous admixtureinto a structural element, and freezing said admixture.

6. A method of obtaining a strong, substantially homogeneous, frozenliquid composition comprising: dissolving a sodium carboxymethylcellulose thickening agent into water in an amount sufficient toincrease the viscosity of the water, admixing a fibrous filler into saidliquid to obtain a substantially homogeneous admixture, forming saidsubstantially homogeneous admixture into a struc tural element, andfreezing said admixture.

References Cited by the Examiner UNITED STATES PATENTS 1,415,325 2/1919Ellis 62-1 X 2,291,680 8/1942 Bi'llner 621 X 2,793,963 5/1957 Tym 6266 X2,800,456 7/1957 Shepherd 621 X 3,205,665 9/1965 Van Horn 61-.5

ROBERT A. OLEARY, Primary Examiner.

W. WAYN Assistant Ex m n r.

1. A METHOD OF OBTAINING A STRONG, SUBSTANTIALLY HOMOGENEOUS AND BUBBLE-FREE FROZED ADMIXTURE OF LIQUID AND A RELATIVELY LARGE AMOUNT OF FIBROUS FILLER WHICH ORDINARILY DOES NOT REMAIN SUSPENDED IN SAID LIQUID ONCE DISPERSED THEREIN AND WHICH ORDINARILY PROMOTES THE FORMATION OF AIR BUBBLES IN THE ADMIXTURE COMPRISING: DISSOLVING A THICKENING AGENT INTO SAID LIQUID IN AN AMOUNT SUFFICIENT TO INCREASE THE VISCOSITY OF SAID LIQUID, DISSOLVING A WETTING AGENT INTO SAID LIQUID IN AN AMOUNT SUFFICIENT TO ENSURE THE WETTING OF SAID FIBROUS FILLER BY SAID LIQUID, ADMIXING A FIBROUS FILLER INTO SAID LIQUID TO OBTAIN A SUBSTANTIALLY HOMOGENEOUS ADMIXTURE, AND FREEZING SAID ADMIXTURE. 